In recent years, a number of different types of automated scrubbers for precision cleaning of silicon wafers have been developed. Typically, such automated scrubbers include two cassettes, a load cassette and an unload cassette with a scrubbing station therebetween. In such prior art arrangements, the silicon wafer to be cleaned is typically withdrawn from the load cassette and transferred to the scrubbing station. After cleaning, the scrubbed silicon wafer is then transferred to a different cassette, that is, the unload cassette.
However, such prior art arrangements have not been wholly satisfactory. More particularly, the use of two different cassettes, one for loading the silicon wafers to be cleaned to a scrubbing station and an unload cassette for receiving the wafers after they have been cleaned, results in automated apparatus which is quite complex having many moving parts, which requires costly maintenance and which system is more expensive to produce.
Broadly, it is an object of the present invention to provide an automated material-handling apparatus, such as an automated scrubber, which overcomes one or more of the aforesaid drawbacks. Specifically, it is within the contemplation of the present invention to provide an improved automated scrubber which utilizes only a single cassette for loading and unloading the silicon wafers to and from a scrubbing station.
It is a further object of the present invention to provide an improved automated single-cassette load mechanism for scrubbers which includes a wafer-supporting arm which moves directly through the cassette carrying the wafers to move a selected one of the wafers from its position within the cassette to the scrubbing station and for returning the selected wafer from the scrubbing station to the cassette.